Rev. Winzer (and others) do you believe Calvin believed that all members of the new covenant are elect, saved?
As noted earlier, Calvin didn't work with the internal-external distinction. His most regular way of dealing with the relationship between elect and reprobate in the visible church was to draw attention to the fact of true and false profession. For Calvin the reprobate are not truly in the covenant, and that applies in both Old and New Testaments. So, in whatever sense Calvin rejects the membership of reprobates in the new covenant is the same sense in which he rejects their membership in the old covenant. There is no substantial difference.